I've said this before, but I believe this recent attendance wave has more to do with what WDW was doing when today's parents were children (the big building boom starting from the mid-80s thru the 25th Anniversary), than what WDW has been doing recently. Mom and/or Dad have been waiting 25 years for the day they can return (or visit because their parents always said no) to WDW with their children so they can do all the things that their parents told them "no," and they are going to ban that word from their vocabulary while they are there. That kind of motivation is incredibly difficult to break through and cause people to re-evaluate their vacation decisions. It also makes it easy to jack up the prices without fear of it affecting anything (to a point).
The "Disney is a business" crowd points out regularly, that expecting WDW to be run like it was 25-30 years ago is naive and not in tune with current business realities. So the potential problem is all these parents are walking in with expectations that can't possibly be met. And why things like people waiting most of their life to stay at a monorail resort, only to arrive and find the monorail unavailable for several hours a day can be a big deal. Or planning on doing silly things like doing rope drop and riding Space Mountain 3 times in a row first thing, and being met with FP+ which pretty much limits rides to once or twice per day. What we don't know yet, is what they are telling their friends about their recent WDW vacation and how it's impacting the next wave. I don't even really expect most people to trash it, because that would mean admitting they made some sort of mistake. I sort of expect people to just be silent about it, with the most damaging statements being that they didn't have plans to return.
A 10 year old in 1986 will be 40 years old in 2016. Good chance, they have a 10 year old, and some younger children and have recently visited or will be recently visiting. A 10 year old in 1996 (start of 25th anniversary) will be 30, and is likely just starting their family and might expect to start visiting in 5-10 years. I would expect WDW to continue to see strong attendance during this period, regardless of any decisions Disney makes. If WDW hits any bumps in the road, they have to be the size of boulders in regards to perception of a WDW vacation because it would take a boulder to overcome the inertia WDW currently has in their favor. Where I think the problem will show up is return bookings within this group. WDW was pretty shocked by how many people "returned" for the 25th anniversary and MK attendance surged to 17 million people in 1997 (maybe today's parents final trip as a child?) and that once we move beyond this group, it will never be like this again. My concern is that WDW will have put itself in a Wile E. Coyote situation...so concentrated on that Roadrunner, that they don't realize that they ran off the cliff years ago, but this demographic so willing to do anything, driven by memories of a WDW that no longer exists, shielded them.